Method of rendering fabrics waterrepellent and composition therefor



Patented Mar. 11, 1952 UNITED STATES PATENT OFFICE METHOD OF RENDERING FABRICS WATER- REPELLENT AND COMPOSITION THEREFOR Firth L. Dennett, Midland, Mich., assignor to Dow Corning Corporation, Midland, Mich., a corporation of Michigan No Drawing. Application March 9, 1950, Serial No. 148,733

repellentfabrics with improved laundering and dry cleaning characteristics and improved crease resistance may be obtained by treating them with certain organosiloxanes. Although the method there describedallowed the manufactureof greatly improved water-repellent fabrics, certain improvements are to be desired in the results obtained. For instance, some treated fabrics, particularly the smooth-fibered fabrics, such as acetate rayon and nylon, became too slippery. It was found that in the die cutting of stacks of such fabrics, the slippage of some of the individual pieces resulted in imperfect cuttings, with errors in dimensions and form causing an undesirable number of rejects.

A somewhat related problem was that of 'slippage of the individual yarns in a fabric. This slippage resulted in the obviously undesirable effect of allowing separation of the yarns from one another when the fabric was under stress. The slick, slippery hand of treated smoothfibered fabrics was also undesirable in many applications.

Known methylhydrogenpolysiloxane compositions, when applied to cotton fabrics, have been 9' Claims. (Cl. 117-161) per silicon atom. Fluids of this typemaybe produced by the hydrolysis and condensation of CHsHSiClz alone or by cohydrolyzing and cocondensing it with chlorosilanes such as (CH3)3SiCl; (CH3)2H3EC1; and '(CHalzSiClz. These fluids have the general formula where a has a value of from 1 .0 to 1.5, b has a value of from 0.75 to 1.25, and the sum etc and b has a value of from2.0 to 2.25 inclusive.

(II) A methylpolysiloxane fluid which contains between 2 and 2.1 methyl radicals per silicon atom and which has a viscosity of at least 1,000

centistokes and. preferably less than 100,000

centistokes. Such fluids have been described in the art and are now commercially available. They have the general formula (CI-IsJ tSiO4-n, where nhas a value of from 2.0 1102.1.

(III) A methylpolysiloxaneresin of the general formula where a: has a value of from 1,0 to 1.25. Such resins are well knowntothe art. They maycontain units such as (CI-IalzSiO, '(CHaiaSiOs, or unsubstituted silicon in addition to theGHaSiOrs units which constitute a major portion of the notoriously poor in resistance to laundering.

Treated cotton fabrics have also been found to have too soft a hand, and a more crisp effect has been desired.

It is an obect f the present invention to provide improved methods of rendering fabrics water-repellent.

- -In accordance with the present invention, fabrics are rendered water-repellent by wetting the fabrics witha mixture of three organosiloxane polymers. The wetted fabrics are then heated at a temperature ranging from 100 to 475 F. fora period of from 5 seconds to one hour.

The fabrics which may be treated in accord with themethod of this invention include fabrics of natural flberssuch as cotton, silk, linen, or .wool; and fabrics of synthetic fibers such as nylon, *Orlonfand either viscose or acetate rayon. I

. The three .organosiloxanepolymers used in the "above stated mixture are as follows:

(I) A methylhydrogenpolysiloxane. fluid which contains between 1.0 and 1.5 methyl radicalsand between 0.75 and 1.25hydrogen atoms bonded to silicon per silicon atom,therelbeing a total (of 2.0

2.25 methyl radicals and. sucnhydrogen atoms resin. They may be prepared by methods such as those disclosed in U. S. Patent No. 2,486,162 or French Patent No. 927,276. The preferredrange of methyl radicals per silicon atom is from.1.05 to 1.15. These resins are normallyemployed in solution in an appropriate organic solvent, and are added as a solution to (I) and (II) above.

The mixture is made up of from to 45 per cent by weight of the methylhydrcgenpolysilox ane fluid (I), 10 to per cent of the methylpolysiloxane fluid (II), and 20 to 65per centof the methylpolysiloxane resin (III). As wasstated above, the methylsiloxane resin (III) is preferably added asa solution. Both the amount and type ofsolvent for this solution are immaterial, and the actual weight of solvent present is not included in the to per cent (III) calledfor. The composition of the mixture may be varied within the prescribed limits above in accordance with the fabric to be treated and the desired hand to be obtained.

Catalysts may be added to the organosiloxane mixtureabove, and the mixture then usedto wet the. fabric.

fabricdipped in. a solution of the catalyst. Such catalysts include metallic salts vsuch as sodium bicarbonate and sodiumaluminate, andthe me- Alternatively, the fabric may be; wetted with the organosiloxane mixture and the lysts are not necessary to the practice of the invention; however, since they merely speed-up the curing rate.

The organosiloxane mixture may be applied rectly to the fabric. extend the organosiloxane mixture by diluting with a liquid hydrocarbon, chlorohydrocarbon, ether, or alcohol, such as benzene, dioxane, ethanol, methylene dichloride or the like in order to minimize the amount of siloxane employed.

The organosiloxan-e mixture may likewise be extended by the preparation of an aqueous emulsion, which emulsion preferably contains an emulsifying agent decomposable by heating. The quaternary ammonium halides are examples of such emulsifying agents. They are decomposed on heating for a brief period. Examples of such halides arethe alkylarylammonium chlorides, such as trimethylbenzylammonium chloride and hexadecyldimethylbenzylammonium chloride. Noncationic emulsifying agents, such as the amide condensation products of fatty acids with organic amines, are preferred in the treatment ofv cotton, wool, and rayon. An example of such a noncationic emulsifying agent is the product known as Pluramine 8-100, marketed by the Kearny Manufacturing Company, Inc., Kearny, New Jersey. If desired, the siloxane mixture may be thinned with any of the above indicated solvents in order to facilitate emulsification. After emulsification, the solvent may be removed under vacuum, if desired.

Emulsions of methylhydrogenpolysiloxanes fre: quently liberate hydrogen upon standing. In order-to avoid this effect, it is desirable to add an organic acid such as acetic acid to the emulsion in order to inhibit the evolution of hydrogen. The quaternary ammonium salts function well as emulsifying agents in such acid systems.

, ,The siloxane mixture either straight or as solution or emulsion may be applied to the fabric in any appropriate manner. Thus, the mixture may be applied to the fabric b the use of conventional equipment such as a padder or quetch.

The fabric may then be dried to remove water or solvent.

The material should be applied to the fabric in such an amount that there is a pick-up of between one and five per cent of the organosiloxane mixture (not including solvent on water) based upon-the weight of the fabric. The fabric is then heated to between l'00'and 475 F. for from five seconds to one hour. This heating effects liberation of a major portion of the hydrogen which is bonded to the silicon in the methylhydrogenpolysiloxane. The siloxane present is polymerized by this heating to an insoluble polymer in the fabric, whereby the fabric is rendered permanently hydrophobic. When a heat decomposable emulsifying agent is employed, it is also decomposed during this heating.

The present invention is of particular importance in the hydrophobing of nylon, acetate rayon, and cotton. It has been found that by the use of the mixture of organosiloxanes disclosed fabric which has a more'crisp hand.-

However, itis preferred to The following organosiloxanes were prepared for use in the examples below. Part given are by weight.

' additional 750 parts of benzene were then added to the reaction mixture. The product was washed six times with water and strip distilled 1 at 3 mm. pressure to 115 C. to remove the benzene and the lower boiling products. There were obtained 475 parts of a trimethylsiloxy endblocked methylhydrogenpolysiloxane, which is referred to as product (I) in the examples. A mixture of 9.3 parts by weight of decamethyltetrasiloxane and 735 parts of octame'thylcyclotetrasiloxane was prepared. To this mixture there was added .56 part of KOH. This mixture was then heated at 160 C. for 8 hours. The mixture was then cooled to about C. and CO2 in the form of Dry Ice was added over a period of '30 minutes. This mixture was then filtered and flash distilled to 250 C. at 1 mm. pressure. There were obtained 625 parts of a trimethylsiloxy end-blocked dimethylpolysiloxane fluid having a viscosity of 1,000 centistokes, which is referred to as product (IIA) in the examples. A mixture was prepared of 1.5 parts by weight of decamethyltetrasiloxane and 735 parts of octamethylcyclotetrasiloxane. To this mixture there were then added .56 part of KOI-I. This mixture was then agitated and heated at 160-? C. for 8 hours. The mixture was then cooled to about 100 C. and CO2 in the form of Dry Ice added over a period of 30 minutes. The mixture was then filtered and flash distilled to 250 C. at v1 mm. pressure. There were obtained 630 parts of a trimethylsiloxy end-blocked dimethylpolysiloxanefiuid having a viscosity of 12,500 centistokes, which is referred to as product (IIB) in the examples.

A mixture was prepared of 1.2 parts by weight of decamethyltetrasiloxane and 735 parts of octamethylcyclotetrasiloxane. To this mixture there were then added .56 part of KOI-I. The mixture was then agitated and heated at 160 C. for "8 hours. i The mixture was then cooled to 100 C. and CO2 in the form of Dry Ice added over a period of 30 minutes. The mixture was then filtered and flash distilled to 250 C. at 1 mm. pressure. There were thereby obtained 620 parts of a trimethylsiloxy end-blocked dimethylpolysiloxane having a viscosity of 30,000 centistokes, which is referred to as product (IIC) in the examples.

A mixture of 1345 g. of CHsSlCk and 128 g. of (CH3)2S1C12 was diluted with 500 g. of toluene ,and addedslowly to a mixture of 6,000 g. of water, 500 g. of toluene, and 1,500 g. of n-butanol. The temperature of the reaction mixture was held at less than 25 C, throughout the addition, When the reaction was complete, the organic layer was washed free of HCl, dried over sodium sulfate, and filtered. The filtered resin solution was adjusted to 33 per cent resin solids by'the addition ofa'small amount of toluene. *This resin solutionis referred to as product (IIIA) the examples. 7

A mixture of 1317 g. of CHsSiCla and 130 g. of (Cl-IsiSiCl was diluted with 500 g. of toluene and hydrolyzed by the procedure of (IIIA) above.

asaaace &

After washing, drying,and filtering, the resin solution was adjusted to 33 per cent by weight of resin solids. This solution is referred to in the examples as product (IIIB).

Example 1 Amixture wasmadeof 30 parts of the methylhydrogenpolysiloxanefluid (1),.20 partslof 30,000 centistokes methylpolysiloxane fluid (I), and 150 partsofthe 33 percent methylpclysiloxane resinsolution (IIIA). To this mixture Was added 3133 parts of toluene, giving a 3 per cent solution based onthe organosilicon content. When samples of nylon and acetate rayon are treated with this solution, and then heated at a temperature of 150 C. for IOuminutes, a spray rating (AATCC standard test method 22-41) of 90-100 is obtained. The fabrics have a soft, full hand, and show no slippage eifect when incontact 'With one another.

Erample 2 The .iollowinermixtures weremade:

ylpolysiloxanefluid (I113), 165 parts 33 per I cent (IIIA).

D. 30 parts (1),20 parts 1, 000 centistokes methylpolysiloxane fluid *(IIA), 150 parts 33 per cent (IIIA).

E. BOpartsl-I), "parts l2g500 centistokes methylpolysiloxane fluid (TIE), 150parts 33 per cent (IIIB).

Each mixture wasdiluted to 3 per cent organesilicon content with toluene. Samples of acetate rayon gabardine,,plaineweave nylon, rayon and nylon taffetas, muslin, and cotton twill were dipped in eachsolution and then cured .at 150 C. for 10 minutes. Spray ratings on the treated fabrics ran from 70 to 100, and the following general trends were :noted: As the percentage of methylhydrogenpolysiloxane (I) isdecreased below about 30, (based on the total organosiloxane components), the spray rating gradually decreases. As the percentage of methylpolysiloxane fluid (IIA, B, C) is decreased, the fabrics become less slippery but begin to show a stiffer hand and have less resistance to mark-off or creasing. Increasing this component causes a drop in water-repellency and results in a more slippery fabric, but improves the resistance to markoif. As the percentage of .methylpolyslloxane resin (1111A) is decreased, the slippage of the fabric increases; raising this percentage produces a stiffer fabric with less Water-repellency and a somewhat brash hand. The monomethyl-trimethyl polysiloxane resin (IIIB) compares favorably with the monomethyl-dimethyl polysiloxane resin (IIIA). with the exception that on cotton it imparts somewhat less resistance to laundering. It was indicated that the composition of Example 1 is preferable for maximum water-repelency, wash resistance and resistance to mark-01f; and for minimum slippage of smooth-fibered fabrics.

polysiloxane resin (IIIA). 32 g. of 12,500 centistokes methylpolysiloxane fluid (I13), 48 g. of

e methylhydrogenpolysiloxane :fiuld (I) and 43 g. of methylene dichloride was made. This was added slowly, with extremelyrapid agitation, to a solution of 2 g. of cetyldimethylbenzylammonlum chloride in g; of water. The resultingemulsion was diluted to a 4 per cent concentration of organosiloxane components by the addition of water. Samples of plain-weave nylon were dipped in the 4 per cent emulsion and cured for 5 minutes at 150 C. The cured samples were found to have a spray ratin of 100. A sample was washed for 45 minutes at 130 F. in a 0.5 per cent soap solution. After rinsing and drying, the spray ratingremained unchanged at.100. The treated samples had no undesirable slippage properties.

Example 4 When samples of nylon fabric are treated with the 3 per cent solution of Example 1, and cured for 1 minute at a temperature of 450 results are obtained comparable to the results of the treatment in Example 3.

Example 5 In order to illustrate the eifectof the presence of the methylpolysiloxane resins, two emulsions were prepared as follows:

A. A mixture of 48 'g. of methylhydrogenpolysiloxane fluid (I), 32 g. of 12500 'centistokes methylpolysiloxane fluid (HE), and 40 g. of methylene dichloride was slowly added to a rapidly agitated solution of 3 g. of PluramineS 100"in g. of water. The resulting emulsion was diluted by the addition of water to a 3 per cent concentration of the organosiloxane components.

B. A mixture of 48 g. of methylhydrogenpolysiloxane fluid (I), 32 -g. of 12,500 centistokes methylpolysiloxane fluid (IIB) 40 g. of methylene dichloride, and 120 -g.-0f the 33 per cent solution of methylpolysiloxane resin (IIIA) was slowly added to a rapidlyagitated solution of 4 g. of Pluramine 8-100 in 100 g. of water. The resulting emulsion was diluted with water to a 3 per cent concentration oforganosiloxanes.

Samples of tan poplin, grey poplin, cotton gabardine, and mixed acetate-viscose rayon fabrics were dipped in.-these "emulsions and cured for 10 minutes at 150C. Spray ratings were taken on all samples, then the samples were washed for as minutes at 130 F. in a water solution containing 0.5 per centsoap and 0.2 per cent sodium carbonate. After rinsing and drying, the spray ratings were again determined, and the cycle repeatedthrougha total of three washes. The

initial spray rating and the rating after each wash 1 are tabulated below for both the "A and B treatments.

Spray Rating Fabric Initial 1st Wash 2nd Wash 3rd Wash A B A B A B A B Tan poplin... 100 100 100 70 80 70 80 Grey poplin... 100 100 70 70 80 70 80 Cat. gabar- 1 Ac. and Vis. 70 80 rayon 90 70 70 70 70 70 70 The rayon which had been treated with the "B" emulsion, containing methylpolysiloxane. resin, showed much less slip than that treated with the' "A emulsion. V

That which is claimed is:

-l. The method of rendering organic fabrics water-repellent, which comprises wetting the fabrics with a mixture of from 15 to 45 per cent byweight of a methylhydrogenpolysiloxane fluid of the general formula where a has a, value of from 1.0 to 1.5, b has a value of from 0.75 to 1.25, and the sum of a. and b has a value of from 2.0 to 2.25; to 30 per cent by weight of a methylpolysiloxane fluid containing between 2.0 and 2.1 methyl radicals per silicon atom and having a viscosity of from 1,000 to 100,000 centistokes; and 20 to 65 per cent by weight of a methylpolysiloxane resin of the gen eral formula where a: has a valueof from 1.0 to 1.25; and heating the wetted fabrics at a temperature of 100 F. to 475 F. for a period of from 5 seconds to 1 hour, whereby the fabrics are rendered water-repellent and slip-resistant.

2. The method of rendering organic fabrics water-repellent, which comprises wetting the fabrics with an aqueous emulsion of a mixture of from to 45 per cent by weight of a methylhydrogenpolysiloxane fluid of the general formula where a has a value of from 1.0 to 1.5, b has a value of from 0.75 to 1.25, and the sum of a and b has a value of from 2.0 to 2.25; '10 to 30 per cent by weight of a methylpolysiloxane fluid containing between 2.0 and 2.1 methyl radicals per silicon atom and having a viscosity of from 1,000 to 100,000 centistokes; nd to 65 per cent by weight of a methylpolysiloxane resin of the general formula 15 to 45 per cent by weight of a methylhydrogenpolysiloxane fluid of the general formula where a. has a value of from 1.0 to 1.5, b has a value of from 0.75 to 1.25, and the sum of a and b has a value of from 2.0 to 2.25; 10 to 30 per cent by weight of a methylpolysiloxane fluid containing between 2.0 and 2.1 methyl radicals per silicon atom and having a viscosity of from 1,000 to 100,000 centistokes; and 20 to per cent by weight of a methylpolysiloxane resin of the general formula I l where a: has a value of from 1.0 to 1.25.

4. The method of claim 1 in which the methylhydrogenpolysiloxane fluid is a trimethylsiloxy end-blocked methylhydrogenpolysiloxane, the methylpolysiloxane fluid is a trimethylsiloxy endblocked dimethylpolysiloxane, and in which the methylpolysiloxane resin is a copolymer containing (CH3) $101.5 units and units of the group consisting of (CH3)2SiO and (CHa)sSiO.5 units.

5. The method of claim 2 in which the methylhydrogenpolysiloxane fluid is a trimethylsiloxy end-blocked methylhydrogenpolysiloxane, the methylpolysiloxane fluid is a trimethylsiloxy endblocked dimethylpolysiloxane, and in which the methylpolysiloxane resin is a copolymer containing.(CH3) Si01.5 units and units of the group con- 7 sisting of (CH3) 2SiO and (CH3)3SiO.5 units.

6. The method of claim 5 in which the emulsifying agent is a quaternary ammonium halide.

7. The organosiloxane mixture of claim 3 in which the methylhydrogenpolysiloxane fluid is a trimethylsiloxy end-blocked methylhydrogenpolysiloxane, the methylpolysiloxane fluid is a trimethylsiloxy end-blocked dimethylpolysiloxane, and in which the methylpolysiloxane resin is a copolymer containing (CH3) SiO1.5 units and units of the group consisting of (CHanSiO and (CH3)3SiO.5 units.

8. An aqueous emulsion of mixture of claim 7.

9. The emulsion of claim 8 in which the emulsifying agent is a quaternary ammonium halide.

FIRTH L. DENNETT.

the organosiloxane REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,386,259 Norton Oct. 9, 1945 2,392,805 Biefeld Jan. 15, 194.6 

1. THE METHOD OF RENDERING ORGANIC FABRICS WATER-REPELLENT, WHICH COMPRISES WETTING THE FABRICS WITH A MIXTURE OF FROM 15 TO 45 PER CENT BY WEIGHT OF A METHYLHYDROGENOPOLYSILOXANE FLUID OF THE GENERAL FORMULA (CH3)AHBSIO 4-A-B 